When conventional mowers are used to mow the highway areas where guardrails or media safety cables are present, a strip of uncut vegetation is left beneath the guardrail or safety cable. In an attempt to remedy this problem a double cutter head mower has been marketed by others which places cutter heads on opposite sides of the guardrail or cable barrier. However, the performance of this previously marketed mowing machine has not been found to be entirely satisfactory in its adjustability, adaptability and controls to provide safe and satisfactory performance.